Bulb nurseries and snowdrop collectors fear problems with narcissus leaf scorch after the second wettest year on record in 2012.
Somerset-based Avon Bulbs manager Alan Street said: "Chances are the fungus will be worse this spring with the incredible amount of rain last summer and autumn because most fungi like damp. With the continual rain over the summer, the snowdrops didn't have a nice dry rest - a lot of them were under water."
He added: "The increasing number of plant exchanges and trade in snowdrops by enthusiasts mean that the disease is being spread around far more than in the past, so it needs to be more widely publicised.
"With no treatment available to home gardeners, all that they can do is dig up infected plants and dispose of them, and then avoid planting snowdrops in the same place again."
RHS head of horticultural advice Guy Barter said: "Narcissus leaf scorch is a problem for nurseries where plants are grown in close proximity and in large numbers.
"But it's also a problem for collectors who buy a lot of bulbs and plant them close together because they don't have much garden space. In gardens, the snowdrops are often more widely spaced - if they get the disease and die out, that's the end."
Collectable bulbs can cost up to £725 each. The disease is caused by a fungus, Stagonospora curtisii, known as "staggy", which affects bulbs such as daffodils, hippeastrum, Crinum, nerine, Sternbergia and Galanthus.
It causes weak growth as well as distorted leaves and flowers. Infected bulbs rot below ground and do not reappear above ground in January, when they traditionally bloom.
Symptoms start with tops of emerging leaves dying back and being flushed with red. Infection then spreads to leaf bases as fungal spores produced by the initial infection are washed down by rain. The layers of the bulbs become covered with orange patches, which then start to rot. Spores remain active in the soil for up to five years.
"I have had customers ringing up and asking whether their snowdrops will be all right," said Street. "Hopefully, most will be okay, but some will suffer."
Abi Rayment of Dove Associates added: "Scorch has a similar life cycle to smoulder. Control used to be based on preventive treatments using chlorothalonil.
"There are currently no official onor off-label approvals listing this specific disease, but we know that extensions of authorisation for minor uses will provide an additional control effect on this disease.
"The Horticultural Development Company has done extensive work on bulb dipping and hot water treatment, which not only controls Fusarium oxysporum but other diseases like scorch."
£725 - The highest price that has been paid for a single snowdrop bulb.